The world finds a myriad of electronic devices available to the user. For the user to take advantage of what a particular device has to offer, he must be able to interface with it. On such interface is the knob, found on practically every mechanical or electronic device. People learn to use this interface at an early age and quickly associate the turning of the knob as changing how the device operates—for instance, turn the knob clockwise to go to “high” and turn the knob counter-clockwise to go to “low.” As in the case of a radio, the knob may be attached to a potentiometer; the user turns up the volume and the resistance of the potentiometer decreases, so that more of the output power from the radio's amplifier is directed to the speakers. During the turning of the knob, the user may encounter clicks and pops owing to a less than solid electrical connection of the rotating conductive contact and the surface of the variable resistor. Such pops may diminish the user's enjoyment of the listening experience, at a minimum or such pops may be large transient voltages sent to the speakers that damage them.
Furthermore, the mechanical nature of the potentiometer may limit its usefulness in small portable devices (i.e., PDAs, smart phones, tablet computers, etc.); the mechanics can only scale so far.
There exists a need for the familiar knob-based user interface which overcomes the shortcomings of a mechanical control that is suitable for modern electronic apparatus.